Commit | Line | Data |
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15fae37d | 1 | /* |
c103de24 | 2 | * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders |
15fae37d DB |
3 | * |
4 | * Copyright (C) 2007 David Brownell | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | ||
21 | #include <linux/kernel.h> | |
22 | #include <linux/slab.h> | |
d120c17f | 23 | #include <linux/gpio.h> |
15fae37d DB |
24 | #include <linux/i2c.h> |
25 | #include <linux/i2c/pcf857x.h> | |
bb207ef1 | 26 | #include <linux/module.h> |
15fae37d | 27 | |
15fae37d | 28 | |
3760f736 JD |
29 | static const struct i2c_device_id pcf857x_id[] = { |
30 | { "pcf8574", 8 }, | |
4ba2ccb8 | 31 | { "pcf8574a", 8 }, |
3760f736 JD |
32 | { "pca8574", 8 }, |
33 | { "pca9670", 8 }, | |
34 | { "pca9672", 8 }, | |
35 | { "pca9674", 8 }, | |
36 | { "pcf8575", 16 }, | |
37 | { "pca8575", 16 }, | |
38 | { "pca9671", 16 }, | |
39 | { "pca9673", 16 }, | |
40 | { "pca9675", 16 }, | |
1673ad52 DB |
41 | { "max7328", 8 }, |
42 | { "max7329", 8 }, | |
3760f736 JD |
43 | { } |
44 | }; | |
45 | MODULE_DEVICE_TABLE(i2c, pcf857x_id); | |
46 | ||
15fae37d DB |
47 | /* |
48 | * The pcf857x, pca857x, and pca967x chips only expose one read and one | |
49 | * write register. Writing a "one" bit (to match the reset state) lets | |
50 | * that pin be used as an input; it's not an open-drain model, but acts | |
51 | * a bit like one. This is described as "quasi-bidirectional"; read the | |
52 | * chip documentation for details. | |
53 | * | |
54 | * Many other I2C GPIO expander chips (like the pca953x models) have | |
55 | * more complex register models and more conventional circuitry using | |
56 | * push/pull drivers. They often use the same 0x20..0x27 addresses as | |
57 | * pcf857x parts, making the "legacy" I2C driver model problematic. | |
58 | */ | |
59 | struct pcf857x { | |
60 | struct gpio_chip chip; | |
61 | struct i2c_client *client; | |
1673ad52 | 62 | struct mutex lock; /* protect 'out' */ |
15fae37d | 63 | unsigned out; /* software latch */ |
0c65ddd4 KM |
64 | |
65 | int (*write)(struct i2c_client *client, unsigned data); | |
66 | int (*read)(struct i2c_client *client); | |
15fae37d DB |
67 | }; |
68 | ||
69 | /*-------------------------------------------------------------------------*/ | |
70 | ||
71 | /* Talk to 8-bit I/O expander */ | |
72 | ||
0c65ddd4 | 73 | static int i2c_write_le8(struct i2c_client *client, unsigned data) |
15fae37d | 74 | { |
0c65ddd4 | 75 | return i2c_smbus_write_byte(client, data); |
15fae37d DB |
76 | } |
77 | ||
0c65ddd4 | 78 | static int i2c_read_le8(struct i2c_client *client) |
15fae37d | 79 | { |
0c65ddd4 | 80 | return (int)i2c_smbus_read_byte(client); |
15fae37d DB |
81 | } |
82 | ||
15fae37d DB |
83 | /* Talk to 16-bit I/O expander */ |
84 | ||
0c65ddd4 | 85 | static int i2c_write_le16(struct i2c_client *client, unsigned word) |
15fae37d DB |
86 | { |
87 | u8 buf[2] = { word & 0xff, word >> 8, }; | |
88 | int status; | |
89 | ||
90 | status = i2c_master_send(client, buf, 2); | |
91 | return (status < 0) ? status : 0; | |
92 | } | |
93 | ||
94 | static int i2c_read_le16(struct i2c_client *client) | |
95 | { | |
96 | u8 buf[2]; | |
97 | int status; | |
98 | ||
99 | status = i2c_master_recv(client, buf, 2); | |
100 | if (status < 0) | |
101 | return status; | |
102 | return (buf[1] << 8) | buf[0]; | |
103 | } | |
104 | ||
0c65ddd4 KM |
105 | /*-------------------------------------------------------------------------*/ |
106 | ||
107 | static int pcf857x_input(struct gpio_chip *chip, unsigned offset) | |
15fae37d DB |
108 | { |
109 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); | |
1673ad52 | 110 | int status; |
15fae37d | 111 | |
1673ad52 | 112 | mutex_lock(&gpio->lock); |
15fae37d | 113 | gpio->out |= (1 << offset); |
0c65ddd4 | 114 | status = gpio->write(gpio->client, gpio->out); |
1673ad52 DB |
115 | mutex_unlock(&gpio->lock); |
116 | ||
117 | return status; | |
15fae37d DB |
118 | } |
119 | ||
0c65ddd4 | 120 | static int pcf857x_get(struct gpio_chip *chip, unsigned offset) |
15fae37d DB |
121 | { |
122 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); | |
123 | int value; | |
124 | ||
0c65ddd4 | 125 | value = gpio->read(gpio->client); |
15fae37d DB |
126 | return (value < 0) ? 0 : (value & (1 << offset)); |
127 | } | |
128 | ||
0c65ddd4 | 129 | static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value) |
15fae37d DB |
130 | { |
131 | struct pcf857x *gpio = container_of(chip, struct pcf857x, chip); | |
132 | unsigned bit = 1 << offset; | |
1673ad52 | 133 | int status; |
15fae37d | 134 | |
1673ad52 | 135 | mutex_lock(&gpio->lock); |
15fae37d DB |
136 | if (value) |
137 | gpio->out |= bit; | |
138 | else | |
139 | gpio->out &= ~bit; | |
0c65ddd4 | 140 | status = gpio->write(gpio->client, gpio->out); |
1673ad52 DB |
141 | mutex_unlock(&gpio->lock); |
142 | ||
143 | return status; | |
15fae37d DB |
144 | } |
145 | ||
0c65ddd4 | 146 | static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value) |
15fae37d | 147 | { |
0c65ddd4 | 148 | pcf857x_output(chip, offset, value); |
15fae37d DB |
149 | } |
150 | ||
151 | /*-------------------------------------------------------------------------*/ | |
152 | ||
d2653e92 JD |
153 | static int pcf857x_probe(struct i2c_client *client, |
154 | const struct i2c_device_id *id) | |
15fae37d DB |
155 | { |
156 | struct pcf857x_platform_data *pdata; | |
157 | struct pcf857x *gpio; | |
158 | int status; | |
159 | ||
160 | pdata = client->dev.platform_data; | |
a342d215 BD |
161 | if (!pdata) { |
162 | dev_dbg(&client->dev, "no platform data\n"); | |
a342d215 | 163 | } |
15fae37d DB |
164 | |
165 | /* Allocate, initialize, and register this gpio_chip. */ | |
166 | gpio = kzalloc(sizeof *gpio, GFP_KERNEL); | |
167 | if (!gpio) | |
168 | return -ENOMEM; | |
169 | ||
1673ad52 DB |
170 | mutex_init(&gpio->lock); |
171 | ||
0c65ddd4 KM |
172 | gpio->chip.base = pdata ? pdata->gpio_base : -1; |
173 | gpio->chip.can_sleep = 1; | |
174 | gpio->chip.dev = &client->dev; | |
175 | gpio->chip.owner = THIS_MODULE; | |
176 | gpio->chip.get = pcf857x_get; | |
177 | gpio->chip.set = pcf857x_set; | |
178 | gpio->chip.direction_input = pcf857x_input; | |
179 | gpio->chip.direction_output = pcf857x_output; | |
180 | gpio->chip.ngpio = id->driver_data; | |
15fae37d DB |
181 | |
182 | /* NOTE: the OnSemi jlc1562b is also largely compatible with | |
183 | * these parts, notably for output. It has a low-resolution | |
184 | * DAC instead of pin change IRQs; and its inputs can be the | |
185 | * result of comparators. | |
186 | */ | |
187 | ||
188 | /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f; | |
189 | * 9670, 9672, 9764, and 9764a use quite a variety. | |
190 | * | |
191 | * NOTE: we don't distinguish here between *4 and *4a parts. | |
192 | */ | |
3760f736 | 193 | if (gpio->chip.ngpio == 8) { |
0c65ddd4 KM |
194 | gpio->write = i2c_write_le8; |
195 | gpio->read = i2c_read_le8; | |
15fae37d DB |
196 | |
197 | if (!i2c_check_functionality(client->adapter, | |
198 | I2C_FUNC_SMBUS_BYTE)) | |
199 | status = -EIO; | |
200 | ||
201 | /* fail if there's no chip present */ | |
202 | else | |
203 | status = i2c_smbus_read_byte(client); | |
204 | ||
205 | /* '75/'75c addresses are 0x20..0x27, just like the '74; | |
206 | * the '75c doesn't have a current source pulling high. | |
207 | * 9671, 9673, and 9765 use quite a variety of addresses. | |
208 | * | |
209 | * NOTE: we don't distinguish here between '75 and '75c parts. | |
210 | */ | |
3760f736 | 211 | } else if (gpio->chip.ngpio == 16) { |
0c65ddd4 KM |
212 | gpio->write = i2c_write_le16; |
213 | gpio->read = i2c_read_le16; | |
15fae37d DB |
214 | |
215 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) | |
216 | status = -EIO; | |
217 | ||
218 | /* fail if there's no chip present */ | |
219 | else | |
220 | status = i2c_read_le16(client); | |
221 | ||
a342d215 BD |
222 | } else { |
223 | dev_dbg(&client->dev, "unsupported number of gpios\n"); | |
224 | status = -EINVAL; | |
225 | } | |
15fae37d DB |
226 | |
227 | if (status < 0) | |
228 | goto fail; | |
229 | ||
230 | gpio->chip.label = client->name; | |
231 | ||
232 | gpio->client = client; | |
233 | i2c_set_clientdata(client, gpio); | |
234 | ||
235 | /* NOTE: these chips have strange "quasi-bidirectional" I/O pins. | |
236 | * We can't actually know whether a pin is configured (a) as output | |
237 | * and driving the signal low, or (b) as input and reporting a low | |
238 | * value ... without knowing the last value written since the chip | |
239 | * came out of reset (if any). We can't read the latched output. | |
240 | * | |
241 | * In short, the only reliable solution for setting up pin direction | |
242 | * is to do it explicitly. The setup() method can do that, but it | |
243 | * may cause transient glitching since it can't know the last value | |
244 | * written (some pins may need to be driven low). | |
245 | * | |
246 | * Using pdata->n_latch avoids that trouble. When left initialized | |
247 | * to zero, our software copy of the "latch" then matches the chip's | |
248 | * all-ones reset state. Otherwise it flags pins to be driven low. | |
249 | */ | |
49946f68 | 250 | gpio->out = pdata ? ~pdata->n_latch : ~0; |
15fae37d DB |
251 | |
252 | status = gpiochip_add(&gpio->chip); | |
253 | if (status < 0) | |
254 | goto fail; | |
255 | ||
256 | /* NOTE: these chips can issue "some pin-changed" IRQs, which we | |
257 | * don't yet even try to use. Among other issues, the relevant | |
258 | * genirq state isn't available to modular drivers; and most irq | |
259 | * methods can't be called from sleeping contexts. | |
260 | */ | |
261 | ||
64842aad | 262 | dev_info(&client->dev, "%s\n", |
15fae37d DB |
263 | client->irq ? " (irq ignored)" : ""); |
264 | ||
265 | /* Let platform code set up the GPIOs and their users. | |
266 | * Now is the first time anyone could use them. | |
267 | */ | |
49946f68 | 268 | if (pdata && pdata->setup) { |
15fae37d DB |
269 | status = pdata->setup(client, |
270 | gpio->chip.base, gpio->chip.ngpio, | |
271 | pdata->context); | |
272 | if (status < 0) | |
273 | dev_warn(&client->dev, "setup --> %d\n", status); | |
274 | } | |
275 | ||
276 | return 0; | |
277 | ||
278 | fail: | |
279 | dev_dbg(&client->dev, "probe error %d for '%s'\n", | |
280 | status, client->name); | |
281 | kfree(gpio); | |
282 | return status; | |
283 | } | |
284 | ||
285 | static int pcf857x_remove(struct i2c_client *client) | |
286 | { | |
287 | struct pcf857x_platform_data *pdata = client->dev.platform_data; | |
288 | struct pcf857x *gpio = i2c_get_clientdata(client); | |
289 | int status = 0; | |
290 | ||
49946f68 | 291 | if (pdata && pdata->teardown) { |
15fae37d DB |
292 | status = pdata->teardown(client, |
293 | gpio->chip.base, gpio->chip.ngpio, | |
294 | pdata->context); | |
295 | if (status < 0) { | |
296 | dev_err(&client->dev, "%s --> %d\n", | |
297 | "teardown", status); | |
298 | return status; | |
299 | } | |
300 | } | |
301 | ||
302 | status = gpiochip_remove(&gpio->chip); | |
303 | if (status == 0) | |
304 | kfree(gpio); | |
305 | else | |
306 | dev_err(&client->dev, "%s --> %d\n", "remove", status); | |
307 | return status; | |
308 | } | |
309 | ||
310 | static struct i2c_driver pcf857x_driver = { | |
311 | .driver = { | |
312 | .name = "pcf857x", | |
313 | .owner = THIS_MODULE, | |
314 | }, | |
315 | .probe = pcf857x_probe, | |
316 | .remove = pcf857x_remove, | |
3760f736 | 317 | .id_table = pcf857x_id, |
15fae37d DB |
318 | }; |
319 | ||
320 | static int __init pcf857x_init(void) | |
321 | { | |
322 | return i2c_add_driver(&pcf857x_driver); | |
323 | } | |
2f8d1197 DB |
324 | /* register after i2c postcore initcall and before |
325 | * subsys initcalls that may rely on these GPIOs | |
326 | */ | |
327 | subsys_initcall(pcf857x_init); | |
15fae37d DB |
328 | |
329 | static void __exit pcf857x_exit(void) | |
330 | { | |
331 | i2c_del_driver(&pcf857x_driver); | |
332 | } | |
333 | module_exit(pcf857x_exit); | |
334 | ||
335 | MODULE_LICENSE("GPL"); | |
336 | MODULE_AUTHOR("David Brownell"); |